This disclosure relates to an in-ear active noise reduction earphone.
U.S. Pat. No. 8,682,001, incorporated here by reference, describes the acoustic and ergonomic structures of an in-ear active noise reduction earphone. A cross-sectional view of the earphone described in that patent, located in an ear, is shown in FIG. 1. The earphone 10 includes an electro-acoustic transducer, or driver, 12, mounted in a housing 14, having a front shell 16 and a rear shell 18. An ear tip 20 couples the housing to the ear. One feature described in that application is a nozzle 22 leading from a cavity 24 defined by the front shell 16 on the front side of the driver 12 into the user's ear canal. The acoustic mass of such a nozzle acts as an acoustic impedance that reduces the variation in the total response of such a headset from an ANR perspective when compared between different users, with different ear anatomy. Achieving uniformity of response through acoustic measures comes at the cost of performance, that is, the amount of sound cancellation that can be provided, is compromised in order to provide a similar response on different users.
We refer to the element to be inserted into or located on one ear as an “earphone.” We refer to a system including two earphones, for use by one person, as a “set of earphones” or as “headphones.” A set of earphones may also include wiring between the earphones, electronics coupled to the earphones through wired or wireless connections, user interface elements such as switches and displays, and connectors or radios for making wired or wireless connections to signal sources such as telephones, intercoms, and music players.